Due to advantages of stable pictures, vivid images, eliminated radiation, economic space, economic power consumption and the like, Thin Film Transistor-Liquid Crystal Displays (TFT-LCDs) are widely applied to electronic products such as televisions, mobiles, displays and the like, and are dominant in the field of tablet display.
The liquid crystal display shown in FIG. 1 basically comprises a liquid crystal display panel (LCD panel) and a driving apparatus for the liquid crystal display panel, and the driving apparatus comprises components such as a source driver, a gate driver, a timing controller (T-con) and the like; signals transmitted to the liquid crystal display basically comprises image display signals R, G and B, enable signal DE, clock signal MCLK, and vertical synchronization signal Vsync and horizon synchronization signal Hsync. The timing controller transmits an image data signal (DATA), a row start signal (STH), a row latch signal (TP) and a polarity inversion signal (POL) to the source driver, and transmits a column start signal (STV), a column clock signal (CPV) and an output enable signal OE to the gate driver, so as to allow the liquid crystal display panel to display images.
An elementary image display unit of the liquid crystal display panel is a sub-pixel which takes on a capacitance effect in liquid crystal display panel structure, and an image will be displayed as long as a sufficient driving voltage is applied to two terminals thereof; and voltages applied to the two terminals of the capacitor are a common voltage and a data line voltage respectively. Therefore, if positive and negative polarity inversion is not performed on the voltage applied to the two terminals of the capacitor, the sub-pixels displaying the image will be charged for a long time with the same direct current voltage, and then a certain amount of charges will be deposited for a long time in a liquid crystal orientation layer and a liquid crystal layer between the common electrode and the pixel electrode, as shown in FIG. 2; this will cause the sub-pixels to be undesirably displayed, the liquid crystal polarization will be resulted therefrom to the worst extent so that the liquid crystal of the sub-pixels may fail, or image sticking will occur on the liquid crystal display panel even to a minor extent; that is, some background colors will be represented at time of display, and color contrast will be decreased too. Therefore, the signal voltages for driving the sub-pixels need the positive and negative polarity inversion at intervals, and an existing general approach is to alternatively perform polarity inversion between odd and even frames.
Even if the signal voltages with the positive and negative polarity are alternatively applied to the sub-pixels of the liquid crystal display panel, however, it is still possible that the signal voltages finally applied to the sub-pixels of the liquid crystal display panel are undesirable in terms of the positive and negative symmetry due to factors such as original positive and negative voltages provided by the driving circuit being undesirable in terms of symmetry, characteristics of the liquid crystal display panel itself being undesirable, an issue of image signal mode provided by a custom system, signal instability or the like; after the image is display for a long time, due to deflection to a certain polarity as a whole, the issues of the liquid crystal polarization or image sticking will occur generally.